The Mysterious Physics of 7 Everyday Things

By Natalie Wolchover |
October 5, 2011 04:27pm ET

Photo Credit: DOE

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Intro

Physicists have figured out some extremely fine details of the universe, from the radius of black holes to the behavior of subatomic particles neither of which we can even see. It may surprise you to learn, then, that they lack explanations (or have only recently stumbled upon them) for many common phenomena we observe in daily life.

As you'll learn in the following slides, some of the most mysterious things of all may be those that, on the face of it, seem mundane.

Nuts

Photo Credit: Melchoir | Creative Commons

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Nuts

Perhaps you've noticed that, in bowls of mixed nuts, the Brazil nuts always seem to be sitting on top. This is known as the "Brazil nut effect," and the seemingly mundane phenomenon is actually one of the biggest unsolved mysteries in many-body physics the science that describes large quantities of interacting objects.

Among an assortment of things (whether they be nuts, sedimentary deposits, or other objects of varying sizes), larger pieces rise to the top over time in spite of their greater gravitas, while smaller objects tend to sink lower in the pile over time. Perhaps the small stuff is trickling through cracks. Convection currents may also play a role, as might condensation of smaller particles. All of these possibilities and a few more probably contribute to the Brazil nut effect, but no one knows which ones, or to what extent, so no successful computer simulations of the phenomenon have been made.

Not only nut manufacturers, but also physicists, astronomers and geologists would all benefit from an understanding of the effect, so next time you're eating nuts or granola, or fishing the crumbs out of the bottom of a bowl of Doritos, try contemplating the physics involved.

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Foam

Photo Credit: sxc.hu

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Foam

Had a bubble bath today? Maybe not but you've probably shaved, washed dishes, had a latte or beer, or, if you're lucky, eaten a piece of pie topped with a puff of whipped cream.

We encounter foam so often that few of us step back and fully appreciate how weird the stuff really is. For starters, consider this: Is whipped cream a solid, a liquid, or a gas?

According to Douglas Durian, a professor of physics at UCLA, foams are typically 95 percent gas and 5 percent liquid. Somehow these add up to give them certain traits of solids, too. The gas in the foam separates the liquid to form a matrix of tiny bubbles, and if the bubbles' liquid walls are rigid enough, the foam can sometimes keep its shape.

However, no formula exists for predicting exactly how stiff or oozy a foam will be based on the size of its bubbles or the amount of liquid it contains. "The physics of foam is poorly understood," Durian told NASA Science.

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Ice

Photo Credit: Creative Commons | Kafubra

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Ice

A century and a half of scientific inquiry has yet to determine why ice can make you fall down. Scientists agree that a thin layer of liquid water on top of solid ice causes its slipperiness, and that a fluid's mobility makes it difficult to walk on, even if the layer is thin. But there's no consensus as to why ice, unlike most other solids, has such a layer.

Theorists have speculated that it may be the very act of slipping making contact with the ice that melts its surface. Others think the fluid layer is there before the slipper ever arrived, and is somehow generated by the inherent motion of surface molecules.

Cereal

Photo Credit: Dreamstime

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Author Bio

Natalie Wolchover,

Natalie Wolchover was a staff writer for Live Science from 2010 to 2012. She hold a bachelor's degree in physics from Tufts University and has studied physics at the University of California, Berkeley. Follow Natalie on Google+.